An apparatus for producing nano-bodies

ABSTRACT

An apparatus for producing a body, preferably a nano-body, through the introduction of a body-forming fluid into a dispersion medium. The apparatus includes: a fluid housing configured to house a dispersion medium; at least two separated flow paths along which the dispersion medium flows in a laminar flow, at least two of the separated flow paths converging at a flow-merge location; a fluid flow arrangement which, in use, causes the dispersion medium to flow along each flow path to the flow-merge location; at least one fluid introduction arrangement located at or proximate the flow-merge location configured, in use, to feed the body-forming fluid into the dispersion medium; and a flow constriction arrangement proximate to or following the flow-merge location, which in use, constricts and accelerates the dispersion medium flow proximate to and/or following the flow-merge location.

CROSS-REFERENCE

The present application claims priority from Australian provisionalpatent application No. 2013900814 filed on 6 Mar. 2013, the disclosureof which should be understood to be incorporated into thisspecification.

TECHNICAL FIELD

The present invention generally relates to an apparatus for producingnano-bodies such as particles or fibres, and in particular shortnanofibres. The invention is particularly applicable for producingfibres through the introduction of a body-forming fluid into adispersion medium in the presence of a selected shear rate within thedispersion medium and it will be convenient to hereinafter disclose theinvention in relation to that exemplary application.

BACKGROUND OF THE INVENTION

The following discussion of the background to the invention is intendedto facilitate an understanding of the invention. However, it should beappreciated that the discussion is not an acknowledgement or admissionthat any of the material referred to was published, known or part of thecommon general knowledge as at the priority date of the application.

Short nanofibres can be created by injecting a body-forming fluid, suchas a polymer solution dissolved in water (0.1 to 30% wt/vol of solvent),into a dispersion medium, typically a fluid such as butanol or water,having a viscosity in the range of from about 1 to 100 centiPoise (cP)and moving at 0.1 to 10 m/s. Under these conditions, the polymersolution is drawn out and fractures into short fibres, while the rapidextraction of water from the polymer solution caused by the Butanolcauses the polymer to gel. Fibre size can be controlled by varying theshear force and the polymer concentration, from 15 to 2500 nm diameterand 2 to 20 μm length.

One example of this nanofibre generation method is described ininternational patent application PCT/AU2012/001273, the contents ofwhich are taken to be incorporated into this specification by thisreference. This patent application describes a bench scale experimentalapparatus for performing the described short nanofibre generationmethod. The apparatus consists of a rotary mixer having a 5 cm impellerblade immersed in a beaker of the dispersion medium (Butanol). The bladeis surrounded by a metal ring which includes and is divided by a seriesof 16 circumferentially spaced apart slits having an area of 1.5 cm².For fibre generation, the impeller of the mixer is driven to therequired rotation (and thus shear rate) of between 4000 and 10000 rpm,providing a maximum velocity of the tip of the blade of around 26 m/swhen at 10000 rpm. The selected body-forming fluid is then injected intothe dispersion medium in the beaker through a 25 g needle adjacent toone of the ports on the side of the mixer in close proximity to theblade.

The impeller blade configuration and rotation speed of this bench scaleexperimental apparatus provides a non-laminar (turbulent) system withinthe solvent. This creates significant mixing within the solvent, andthus poor predictability and control over the reagents within thesystem. Moreover, the overall system configuration provides poor controlover rate of polymer injection, and poor control over the positioning ofthe needle tip.

Mercader et al. (2010) Kinetics of fibre solidification, PNAS earlyedition, (www.pnas.org/cgi/doi/10.1073/pnas.1003302107) describes anexperimental apparatus for investigating the kinetics of fibresolidification comprising a capillary pipe with a diameter constriction.The diameter constriction of the pipe was used to produce an extensionalflow a coflowing stream of an aqueous PVA solution. Nanofibres wereproduced by injecting an aqueous dispersion of nanotubes into thecoflowing PVA stream upstream of the constriction. The injectednanotubes underwent bridging coagulation when contacted with the PVAsolution to form a fibre. The fibre was translated and extended by thesurrounding fluid at the center of the pipe at a controlled velocity.The constriction was shown to produce a net tensile stress in the fibrein response to viscous drag. The formed fibre was also shown to fragmentinto shorter length fibres when the surrounding drag forces exceed thetensile strength of the fibre.

While fibres and short fibres are shown to be produced by this method,it is considered that the described apparatus does not providesufficient control of the reagents and flow conditions for thereproducible production of fibres of small diameter. Moreover, asdescribed, there is anticipated to be some difficulties in alignment ofthe injection port with the centre of the capillary.

It would therefore be desirable to provide an improved and/oralternative device for the production of drawn bodies such as fibres,preferably short nano-fibres.

SUMMARY OF THE INVENTION

A first aspect of the present invention provides an apparatus forproducing a body, preferably a nano-body, through the introduction of abody-forming fluid into a dispersion medium. The apparatus includes:

a fluid housing configured to house a dispersion medium;

at least two separated flow paths along which the dispersion mediumflows in a laminar flow, at least two of the separated flow pathsconverging at a flow-merge location;

a fluid flow arrangement which, in use, causes the dispersion medium toflow along each flow path to the flow-merge location;

at least one fluid introduction arrangement located at or proximate theflow-merge location configured, in use, to feed the body-forming fluidinto the dispersion medium; and

a flow constriction arrangement proximate to or following the flow-mergelocation, which in use, constricts and accelerates the dispersion mediumflow proximate to and/or following the flow-merge location.

The laminar flow and the constriction arrangement of the apparatus ofthe present invention form a controlled flow area in the dispersionmedium at and/or following the flow-merge location. The laminar fluidflow environment provides a smooth transition between the flow of thedispersion medium and the flow of the injected body-forming fluid. Thebody-forming fluid is therefore fed into the surrounding controlled flowarea and constricted at and proximate to the flow-merge location. Thisenables improved control over rate of polymer injection as compared tothe previous impeller and ring based system. Furthermore, the use of adedicated fluid introduction arrangement located at or proximate to theflow-merge location improves the positioning of the injection points ascompared to the previous impeller and ring based system.

The combination of laminar flow and the constriction arrangement createa controllable extensional flow which draws and forms the described bodyconfiguration following the flow-merge location of the apparatus. Wherean elongate body, such as a filament, is formed from the introducedbody-forming fluid, the acceleration may also cause that elongate bodyto break, through the creation of the required tensile stress and/orshear rates to allow fragmentation of the elongate body formed by thebody-forming fluid in the dispersion medium.

It should be appreciated that the apparatus can be used to produce avariety of bodies, preferably nano-bodies, of different configurations,shapes and sizes. Examples include rods, ribbons, droplets, particles,filaments, fibres, short fibres, nanofibres, short nanofibres or thelike. In preferred embodiments, the apparatus of the present inventionproduces fibres, preferably nanofibres. The bodies prepared may includea different material core, such as a liquid, gel, solid, gas or similar.

The flow constriction arrangement can include any suitable component orcomponents which constrict and accelerate the flow of the dispersionmedium. The flow constriction can comprise any suitable arrangement,including one or more baffles, weirs, flow constricting apertures,dimension changes such as fluid flow area changes or the like.

In some embodiments (and as described below), one or more hydrofoils canbe used to accelerate and constrict a flow of the dispersion mediumflowing over the hydrofoil.

In some embodiments, the flow constriction arrangement can include achange in a dimension of the fluid housing. The dimension changepreferably comprises a change in the fluid flow cross-sectional area ofthe fluid housing, and more preferably a reduction in the overall fluidflow cross-sectional area from the flow upstream of the flow-mergelocation compared to the flow downstream of the flow-merge location. Forexample, in those embodiments in which the fluid housing comprises aconduit, the flow constriction preferably includes a reduction in thecross-sectional area within the conduit. The fluid housing may thereforeinclude at least first flow section having a first fluid flowcross-sectional area and at least second flow section having a secondfluid flow cross-sectional area, the first fluid flow cross-sectionalarea being greater than the second fluid flow cross-sectional area.

The flow constriction of the second flow section creates an accelerationzone, where the dispersion medium is accelerated along the axis of thefluid housing of the second flow section at the entrance of theconstriction. This acceleration induces the development of anextensional flow field. While not wishing to be limited to any onetheory, it is thought that the body formed from the injectedbody-forming fluid transported by the dispersion medium is stretched inresponse to the acceleration of the dispersion medium. The accelerationresults in a tensile stress in and/or shear stress applied to thatformed body, which can fragment or break the body if the maximum stressexceeds the tensile strength of the body.

The second flow section can commence proximate to or at a distance,preferably a short distance following (downstream of) the flow-mergelocation. In some embodiments, the flow-merge location is spaced awayupstream of the start of the second flow section. Spacing the trailingedge and therefore fluid introduction arrangements apart from the secondflow section creates a separate fluid introduction zone and accelerationzone (as described above).

The flow constriction preferably comprises a reduction in fluid flowcross-sectional area between the first flow section and second flowsection of at least 50%, more preferably at least 60%, yet morepreferably at least 70%, and most preferably at least 75%. In thoseembodiments that include plates, the gap between plates preferablyreduces from between 8 and 15 mm to between 1 and 5 mm, more preferablyfrom between 18 and 11 mm to between 1 and 3 mm, and yet more preferablyfrom 9 mm to 2 mm.

The flow constriction may comprise an immediate dimension change in thefluid housing, for example a conduit. However, it is preferred that thechange is more gradual, having a progressive dimension change. Theprogression may comprise a ramp or smooth transition, stepped or acombination thereof. For example, in some embodiments a third flowsection can be provided located between the first flow section and thesecond flow section of the fluid housing, the third flow section havinga transitory cross-sectional area, preferably tapering cross-sectionalarea, interconnecting the first and second flow sections. Thecross-sectional area of the third flow section preferably comprises abetween 5 and 30°, and preferably about 10° taper between the first flowsection and the second flow section.

The flow constriction may comprise one or a series of dimension changesin the fluid housing. In some embodiments, the flow constrictionincludes two or more dimension changes in the fluid housing. Forexample, the flow constriction may include a first reduction incross-sectional area, followed by a second reduction in cross-sectionalarea, and in some embodiments followed by a third or more reduction incross-sectional area. The series of dimension changes in the fluidhousing may progressively change the dimension of the fluid housing (forexample the cross-sectional area) from an initial dimension to a finaldimension, or may comprise a series of expansion and contraction pointsin which the dimension of the fluid housing varies between an expandeddimension and a contracted dimension. For example, the flow constrictionmay comprise series of reductions and expansions in cross-sectional areabetween a first cross-sectional area and a second (reduced orconstricted) cross-sectional area.

The fluid flow entering the first flow section of the conduit orconduits can have any suitable flow characteristic, including laminar,turbulent or the like, as long as the flow becomes laminar in the firstflow section prior to the flow-merge location. Laminar flow can beachieved using one or more flow aids which modify the flowcharacteristics of the dispersion medium flow prior to the flow-mergelocation. In some embodiments, the arrangement further includes at leastone baffle located in the fluid housing which, in use, contacts thedispersion medium flow before the flow-merge location. In otherembodiments, a flow distributor, such as one or more hydrofoils, can beused to induce laminar flow into the dispersion medium flow through thefirst flow section. Embodiments including hydrofoils are described inmore detail below. In preferred embodiments, the fluid flow arrangementforms a laminar flow in the first flow section. In this respect, alaminar fluid flow can be more easily controlled and the resultspredicted. In those embodiments where the fluid housing includes one ormore conduits through which the dispersion medium flows, the conduit(s)can take a number of configurations. In some embodiments, the conduit(s)comprises a tubular pipe, preferably a pipe having at least one of acircular, square, rectangular or other regular polygon cross-sectionalshape.

In some embodiments, the conduit or conduits include at least two spacedapart plates. The plates are fluidly sealed within the conduit orconduits. The fluid seal may comprise any number of arrangements. Insome embodiments, the plates can be housed within a fluid tight casing,preferably fluidly sealed within a fluid tight conduit, for example atubular conduit. In this embodiment, the plates can be secured orotherwise fastened to adjoining or adjacent surfaces of the fluid tightconduit. In some embodiments, the plates are sealed around the peripheryof each plate, and more preferably around the edges of the plates.

It can be advantageous to be able to vary the dimensions of the fluidhousing and in particular, the dimensions of those parts of the fluidhousing through which the dispersion medium flows (in the relevantembodiments). For example, where conduit(s) includes at least two spacedapart plates, it can be advantageous to be able to vary the distancebetween the plates. This adjustment can therefore vary the flow area andtherefore the flow velocity of the dispersion medium flowing between thetwo plates and to and over the hydrofoil.

The flow constriction arrangement can create shear stress in thedispersion medium creating conditions allowing fragmentation of anybody, particularly elongate bodies such as filaments in the dispersionmedium. The flow constriction arrangement preferably creates a shear inthe dispersion medium at the trailing edge of the hydrofoil where thefluid has a linear speed of at least 0.1 m/s, preferably between 0.2 to20 m/s, more preferably between 0.5 and 10 m/s, yet more preferablybetween 1 to 10 m/s. In some embodiments, the flow constrictionarrangement can create a shear stress in the range of from about 100 toabout 190,000 cP/sec.

The fluid introduction arrangement of the present invention is used tointroduce the body-forming fluid into the dispersion medium at orproximate the flow-merge location of the apparatus. The body-formingfluid may be introduced to the dispersion medium using a suitabletechnique. In some embodiments, the body-forming fluid is injected intothe dispersion medium. The body-forming fluid may be injected into thedispersion medium at a rate in a range selected from about 0.0001 L/hrto about 10 L/hr, or preferably from about 0.1 L/hr to 10 L/hr.

When the body-forming fluid is a body-forming solution, such as apolymer solution, the body-forming solution may be injected into thedispersion medium at a rate in a range selected from the groupconsisting of from about 0.0001 L/hr to 10 L/hr, from about 0.001 L/hrto 10 L/hr, or from about 0.1 L/hr to 10 L/hr.

A person skilled in the relevant art would understand that the rate atwhich a body-forming fluid is introduced to the dispersion medium may bevaried according to the scale on which the process of the invention iscarried out, the volume of body-forming fluid employed, and the desiredtime for introducing a selected volume of body-forming fluid to thedispersion medium. In some embodiments it may be desirable to introducethe body-forming fluid into the dispersion medium at a faster rate thismay assist in the formation of fibres with smoother surfacemorphologies. The injection speed may be regulated by means of a pump,such as for example a syringe pump or a peristaltic pump.

The fluid introduction arrangement can be a separate element insertedinto the flow-merge location, for example a needle or other conduit, orintegrated into a body or component located at the flow-merge location.When formed in a body or component located at the flow-merge location,the fluid introduction arrangement includes at least one aperture,preferably located at or on said body or component. The aperture ispreferably fluidly linked to a conduit or channel formed or housedwithin said body or component through which the body-forming fluid isfed.

In some embodiments, one or more of the apertures can be fluidlyconnected to at least two different body-forming fluids. This enables afibre to be formed including two different materials. The body-formingfluid may be combined in various ways. In some embodiments, the two ormore body-forming fluids may be intermixed prior to being introducedinto the dispersion medium. In other embodiments, the two or morebody-forming fluids may be intermixed proximate or at the point thebody-forming fluids are introduced into the dispersion medium. Forexample, one or more of the apertures may be fluidly connected to atleast two conduits or channels through which at least one body-formingfluid flows, each conduit or channel joining at a merge section locatedproximate to the at least one aperture. The merge section preferablyincludes a short conduit or channel fluidly connected to the at leastone aperture. In some embodiments, the merge section comprises a Y or Tjunction.

In some embodiments, the fluid introduction arrangement includes atleast two proximate apertures, each aperture being fluidly connected toat least one body-forming fluid. This enables the respectivebody-forming fluids to overlap, intertwine or at least interact in someway when introduced into the dispersion medium. Subsequent fibreformation may therefore create an intertwined, mixed or otherwiseinterconnected fibre configuration. In some embodiments, at least two ofthe apertures are fluidly connected to different body-forming fluids.This enables fibre configurations to be formed with two differentmaterials having an intertwined, mixed or otherwise interconnected fibreconfiguration.

In some embodiments, at least two of the apertures overlap. In suchembodiments, at least two of the apertures can be arranged with a firstaperture enclosed within a second aperture. In some forms, three or moreof the apertures can be configured in an overlapping configuration. Insome forms, the two apertures may be concentrically arranged. Forexample, one aperture (the inner aperture) may be fully or partiallyenclosed by another aperture (the outer aperture). This can produce afibre within fibre configuration, where a first fibre is encapsulated orotherwise formed within another fibre. A first material can beencapsulated within a second material in those embodiments in which theat least two of the at least two apertures are fluidly connected todifferent body-forming fluids.

The apertures of the fluid introduction arrangements can have a numberof different shapes and configurations. In some embodiments, the fluidintroduction arrangements have a circular shape. However, it should beappreciated that any number of shapes could be possible including starshaped, cross shaped, oval shaped, any number of regular polygons suchas triangular, square, rectangular, pentagonal, octagonal or the like.

Laminar flow in the at least two separated flow paths can be created inany suitable manner. In some embodiments, the separate flow paths of atleast two of the separated flow paths comprise separate flow conduits.In this embodiment, laminar flow can be created in those separateconduits through control of the flow characteristics in each of thoseconduits. For example, the fluid flow arrangement could be controlled toprovide the required flow velocity for laminar flow in the separateconduits. Furthermore, the configuration of the conduits could beoptimised for laminar flow. In such embodiments, the flow constrictionarrangement would comprise a reduction of the outflow cross-sectionalarea as compared to the combined inflow cross-sectional area of the atleast two separate flow conduits proximate to or following theflow-merge location.

In other embodiments, the at least two separated flow paths can beseparated by at least one hydrofoil located in the fluid housing, thehydrofoil having a leading face and a trailing edge, the fluid flowarrangement causing the dispersion medium to flow in a laminar flow fromthe leading face to the trailing edge thereof.

A second aspect of the present invention provides an apparatus forproducing fibres by introducing a fibre forming liquid into a dispersionmedium, the apparatus including:

-   -   a fluid housing configured to house a dispersion medium;    -   at least one hydrofoil located in the fluid housing, the        hydrofoil having a leading face and a trailing edge;    -   at least one fluid introduction arrangement located at or        proximate the trailing edge of at least one of the hydrofoils        configured, in use, to feed the fibre forming liquid into the        dispersion medium housed in the fluid housing; and    -   a fluid flow arrangement which, in use, causes the dispersion        medium to flow across the hydrofoil from the leading face to the        trailing edge thereof.

The hydrofoil of the apparatus of the present invention creates acontrolled flow area in the dispersion medium at and/or following thetrailing edge of the hydrofoil. The hydrofoil is designed to accelerateand constrict the flow of dispersion medium flowing over the hydrofoilin order to form an extensional flow which draws and forms a fibrouspolymer filament at the trailing edge of the hydrofoil. The accelerationmay also cause the filament to break, through the creation of therequired tensile stress and/or shear rates to allow fragmentation of afilament formed by the body-forming fluid in the dispersion medium, toform short fibres.

The hydrofoil also creates a laminar fluid flow environment over theflow surfaces and at and/or proximate its trailing edge. This provides asmooth transition between flow of the dispersion medium and the flow ofthe injected body-forming fluid. The body-forming fluid is therefore fedinto the surrounding controlled flow area and constricted at and/orproximate the hydrofoil, enabling improved control over rate of polymerinjection as compared to the previous impeller and ring based system.Furthermore, the use of a dedicated fluid introduction arrangementlocated at or proximate the trailing edge of at least one of thehydrofoils, and preferably incorporated into the hydrofoil, improves thepositioning of the injection points as compared to the previous impellerand ring based system.

The hydrofoil can have various shapes and configurations. In someembodiments, the leading face of the hydrofoil preferably comprises arounded or curved surface. Furthermore, the trailing edge of thehydrofoil preferably comprises a substantially flat edge. However, itshould be appreciated that other configurations such as rounded, curved,wavy or the like could be used in other embodiments. Additionally, insome embodiments the hydrofoil is substantially symmetrical about thechord line between the leading face and trailing edge of the hydrofoil.As is understood in the art, the chord line of a hydrofoil is a straightline connecting the leading and trailing edges of the hydrofoil.However, again it should be appreciated that other configurations thehydrofoil may a different shapes or configurations about the chord linein other embodiments.

The hydrofoil and leading face and trailing edge can follow any suitablegeometry. In some embodiments, the hydrofoil has a linear geometry. Inother embodiments, the hydrofoil has a cylindrical or ellipticalgeometry, with the leading face and trailing edge having an annularconfiguration, being centred about a hydrofoil center point. Such ahydrofoil would preferably have a toroidal shape, preferably tapered atthe trailing edge. The dispersion medium would preferably flow throughthe inner void and outer surfaces of the hydrofoil.

The hydrofoil preferably includes a tapered body which tapers inthickness between the leading face and the trailing edge. In someembodiments, the tapered body of the hydrofoil comprises between 5 and30°, preferably about 10° taper between the leading face and trailingedges thereof relative to a center line, preferably the chord line,therebetween.

Advantageously, the above preferred configuration creates laminar flowat or proximate to the trailing edge of the hydrofoil.

In order to create a desired flow pattern across the hydrofoil, thetapered body of the hydrofoil may include at least one curve or wavealong the longitudinal length of the body of the hydrofoil, and morepreferably a plurality of curves or waves along said longitudinallength.

The fluid introduction arrangement can be a separate element to thehydrofoil, for example a needle or other conduit inserted at or near thetrailing edge the hydrofoil. However, it is preferred that the fluidintroduction arrangement is formed in the hydrofoil.

When formed in the hydrofoil, the fluid introduction arrangementincludes at least one aperture, preferably located at or on thehydrofoil, at or proximate the trailing edge of the hydrofoil. Theaperture is preferably fluidly linked to a conduit or channel formed orhoused within the hydrofoil through which the body-forming fluid is fed.

In some embodiments, the apparatus includes two or more hydrofoils. Suchmulti-hydrofoil systems may have the hydrofoils aligned side by side,stacked, placed in parallel, in series or the like.

The hydrofoil can include any number of fluid introduction arrangements.Multiple fluid introduction arrangements are preferably used in thoseembodiments that include a longitudinally elongate or otherwise suitablydimensioned hydrofoil. Where the hydrofoil comprises a plurality offluid introduction arrangements, it is preferred that those fluidintroduction arrangements are spaced apart along the longitudinal lengthof each hydrofoil. Similarly, the apparatus may include a plurality ofhydrofoils spaced apart within the fluid housing. Each hydrofoil wouldinclude at least one fluid introduction element located at or proximatethe trailing edge of at least one of each respective hydrofoil.

The hydrofoil preferably includes a central feed conduit fluidlyconnected to each of the fluid introduction arrangements in thoseembodiments in which the hydrofoil includes a plurality of fluidintroduction arrangements. The central feed conduit can be used to feedbody-forming fluid to each of the individual fluid introductionarrangements from a single source. The central feed conduit ispreferably formed within the body of the hydrofoil. In some embodiments,the central feed conduit extends along the longitudinal length of the,or each, hydrofoil. In some embodiments, the central feed conduit iscentred on the cord line of the hydrofoil. Though, it should beappreciated that the central feed conduit could be positioned at anysuitable location within or outside of the hydrofoil.

In some embodiments, the flow constriction arrangement includes both ahydrofoil and a change in the cross-sectional area of the fluid housingin order to constrict and accelerate the flow of the dispersive mediumin the fluid housing. Again, in those embodiments in which the fluidhousing comprises a conduit, the flow constriction preferable comprisesa change in the cross-sectional area within the conduit. In suchembodiments, the conduit preferably includes at least first flow sectionhaving a first cross-sectional area and at least second flow sectionhaving a second cross-sectional area, the first cross-sectional areabeing greater than the second cross-sectional area.

The second flow section can commence proximate to or a distance,preferably a short distance following (downstream of) the trailing edgeof the hydrofoil. In some embodiments, the trailing edge of thehydrofoil is spaced away upstream of the start of the second flowsection. Spacing the trailing edge and therefore fluid introductionarrangements apart from the second flow section creates a separate fluidintroduction zone and acceleration zone (as described above).

The hydrofoil is preferably located in a third flow section positionedbetween the first and second flow sections of the conduit. The thirdflow section has a transitory cross-sectional area, preferably taperingcross-sectional area, interconnecting the first and second flowsections. The taper of the third flow section preferably substantiallymatches the taper between the leading face and trailing edge of thehydrofoil.

Any suitable fluid housing can be used, depending on the configurationof the apparatus. In some embodiments, the fluid housing can include atleast one conduit through which the dispersion medium flows. In otherembodiments, the fluid housing can include a reservoir in which thedispersion medium is held. One or more combination of theseconfigurations also possible. In each embodiment, the dispersion mediumis preferably recycled through the fluid housing.

The fluid flow arrangement can take various forms depending on theoverall configuration of the apparatus.

In some embodiments, the fluid flow arrangement comprises a pumpingarrangement for pumping the dispersion medium along the separated flowpaths. The dispersion medium can therefore be pumped at a desired flowrate to create laminar flow and to create the desired flow accelerationof the dispersion medium and entrained formed body within the flowconstriction arrangement. In this embodiment, the fluid housingpreferably comprises a conduit through which the dispersion mediumflows.

In other embodiments, the fluid flow arrangement comprises a rotatableelement, driven or otherwise moved to rotate the hydrofoil within thefluid housing. In this embodiment, the fluid housing preferablycomprises a suitable reservoir in which the dispersion medium is held.The reservoir can be held in a receptacle, container, vessel or otherbulk liquid retaining body. Suitable examples include a mixing vessel,such as a beaker, bucket, drum, or larger process vessel. The rotatableelement preferably comprises a drive element, such as a motor, connectedto a shaft or other driven element. The at least one hydrofoil istherefore preferably connected to the shaft, preferably at or near thebase of the shaft. The fluid flow arrangement preferably comprises arotor or stirrer element of a mixer. In those embodiments which includehydrofoils, the hydrofoil preferably comprises part of a driven impellerof the rotor or stirrer element. In these embodiments, the hydrofoil isrotatably driven in the dispersion medium, to create the necessary shearforce within that fluid.

In yet other embodiments, a combination of the above two embodiments mayalso be possible, where the fluid flow arrangement comprises a pumpingarrangement for pumping the dispersion medium in the separate flow pathsand a rotatable element, driven or otherwise moved to rotate the acomponent of the apparatus, for example a hydrofoil, within the fluidhousing.

The fluid housing may include one or more flow aids which modify theflow characteristics of the dispersion medium flow prior to theflow-merge location. In some embodiments, the arrangement furtherincludes at least one baffle located in a location in the housing which,in use, contacts the dispersion medium flow before the flow-mergelocation. In those embodiments in which the fluid housing comprises aconduit, the baffles are preferably located in the conduit upstream ofthe flow-merge location.

A large number of body-forming fluids and dispersion mediums can be usedin the apparatus of the present invention. Suitable examples aredescribed in detail in International application No. PCT/AU2012/001273published as WO 2013056312 A1, the contents of which are incorporatedinto this specification by this reference.

The body-forming fluid is preferably a flowable viscous liquid andincludes at least one body-forming substance. In exemplary embodiments,the dispersion medium employed in the process of the invention is aliquid that is generally of lower viscosity than the body-forming fluid.The relationship between the viscosity of the body-forming fluid (μ1) tothe viscosity of the dispersion medium (μ2) may be expressed as aviscosity ratio (p), where p=μ1/μ2. In one form of the invention, theviscosity ratio is in the range of from about 2 to 100. In someembodiments, the viscosity ratio is in the range of from about 2 to 50.

In some embodiments, the dispersion medium preferably has a viscosity inthe range of from about 1 to 100 centiPoise (cP). In embodiments of theprocess, the dispersion medium has a viscosity in the range of fromabout 1 to 50 centiPoise (cP). In some embodiments, the dispersionmedium has a viscosity in the range of from about 1 to 30 centiPoise(cP), or from about 1 to 15 centiPoise (cP). In some embodiments, thebody-forming fluid has a viscosity in the range of from about 3 to 100centiPoise (cP). In some embodiments, the body-forming fluid has aviscosity in the range of from about 3 to 60 centiPoise (cP).

In preferred embodiments, the body-forming fluid comprises a polymersolution, and the dispersion medium comprises a liquid in which thepolymer is insoluble.

In one set of embodiments the body-forming fluid is in the form of abody-forming solution including at least one body-forming substance in asuitable solvent. The body-forming substance may be a polymer or apolymer precursor, which may be dissolved in the solvent. In someembodiments the body-forming solution includes at least one polymer.

The term “polymer” as used herein refers to a naturally occurring orsynthetic compound composed of covalently linked monomer units. Apolymer will generally contain 10 or more monomer units.

The term “polymer precursor” as used herein refers to a naturallyoccurring or synthetic compound that is capable of undergoing furtherreaction to form a polymer. Polymer precursors may include prepolymers,macromonomers and monomers, which can react under selected conditions toform a polymer.

In one set of embodiments that body-forming solution may be a polymersolution including at least one polymer dissolved or dispersed in asolvent. The polymer solution can be used to form polymer fibres.

The apparatus of the invention may be used to prepare polymer fibresfrom a range of polymer materials. Suitable polymer materials includenatural polymers or derivatives thereof, such as polypeptides,polysaccharides, glycoproteins and combinations thereof, or syntheticpolymers, and co-polymers of synthetic and natural polymers.

In some embodiments, the apparatus of the invention is used to preparefibres from water-soluble or water-dispersible polymers. In suchembodiments, the body-forming fluid may include a water-soluble orwater-dispersible polymer. The body-forming fluid may be a polymersolution including a water-soluble or water-dispersible polymer may bedissolved in an aqueous solvent. In some embodiments, the water-solubleor water-dispersible polymer may be a natural polymer, or a derivativethereof.

In some embodiments the apparatus of the invention is used to preparefibres from organic solvent soluble polymers. In such embodiments, thebody-forming fluid may include an organic solvent soluble polymer. Thebody-forming fluid may be a polymer solution including an organicsolvent soluble polymer dissolved in an organic solvent.

In exemplary embodiments of the apparatus of the invention, thebody-forming fluid may include at least one polymer selected from thegroup consisting of polypeptides, alginates, chitosan, starch, collagen,silk fibroin, polyurethanes, polyacrylic acid, polyacrylates,polyacrylamides, polyesters, polyolefins, boronic acid functionalisedpolymers, polyvinylalcohol, polyallylamine, polyethyleneimine,poly(vinyl pyrrolidone), poly(lactic acid), polyether sulfone andinorganic polymers and copolymers thereof.

In some embodiments, the body-forming substance may be a polymerprecursor. In such embodiments the body-forming fluid may include atleast polymer precursor selected from the group consisting ofpolyurethane prepolymers, and organic/inorganic sol-gel precursors.

The dispersion medium used in the apparatus of the invention includes atleast one suitable liquid. In some embodiments, the dispersion mediumincludes at least one liquid selected from the group consisting of analcohol, an ionic liquid, a ketone solvent, water, a cryogenic liquid,and dimethyl sulfoxide. In exemplary embodiments, the dispersion mediumincludes a liquid selected from the group consisting of C₂ to C₄alcohols. The dispersion medium may include additives or otherproperties that cause the body-forming substance present in thebody-forming fluid to be insoluble, or to otherwise precipitate orgelate, when exposed to the dispersion fluid.

The dispersion medium may include a mixture of two or more liquids, suchas a mixture of water and an aqueous soluble solvent, a mixture of twoor more organic solvents, or a mixture of an organic and an aqueoussoluble solvent. It may also include additives to the dispersion mediumthat chemically interact with the body-forming liquid so as to induceprecipitation or gelation of the dissolved polymer including, but notlimited to, acids or bases, ionic molecules and fixation agents.

The body-forming fluid employed in the apparatus of the invention mayinclude an amount of body-forming substance in the range of from about0.1 to 50% (w/v). In one set of embodiments the body-forming fluid is apolymer solution including an amount of polymer in the range of fromabout 0.1 to 50% (w/v). In embodiments where the body-forming fluidincludes a polymer (such as in a polymer solution or dispersion), thepolymer may have a molecular weight in the range of from about 1×10⁴ to1×10⁷. Polymer concentration and molecular weight may be adjusted toprovide a body-forming fluid of the desired viscosity.

In some embodiments, the body-forming fluid and/or the dispersion mediummay further include at least one additive. The additive may be at leastone selected from the group consisting of particles, crosslinkingagents, plasticisers, multifunctional linkers and coagulating agents.

In exemplary embodiments, the apparatus is used to produce filaments andfibres, preferably nano-fibres, and more preferably short fibres, andyet more preferably short nano-fibres. The fibres produced by thepresent the invention are preferably produced as discontinuous fibres,rather than continuous fibres. Further, the fibres prepared by theprocess of the invention are preferably colloidal (short) fibres. Insome embodiments, fibres prepared by the process have a diameter in therange of from about 15 nm to about 5 μm. In one set of embodiments thatfibres may have a diameter in the range of from about 40 nm to about 5μm. In preferred embodiments, the fibres have a diameter of between 50to 500 nm. Furthermore, the fibres have a length of at least about 1 μm,preferably from about 1 μm to about 3 mm, more preferably between 2 to20 μm.

The bodies, such as fibres, produced using the apparatus of the presentinvention can form part of an article. The bodies may be included on asurface of the article. The article may be medical device or abiomaterial, or an article for filtration or printing applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to thefigures of the accompanying drawings, which illustrate particularpreferred embodiments of the present invention, wherein:

FIG. 1 provides a perspective schematic view of a first embodiment of afibre generation device according to the present invention.

FIG. 2 provides a cross-sectional schematic view of a first embodimentof the flow device for use in the fibre generation device shown in FIG.1.

FIG. 3 provides a cross-sectional schematic view of a second embodimentof the flow device for use in the fibre generation device shown in FIG.1.

FIG. 4 provides a velocity contour diagram for flow over a hydrofoil ofthe hydrofoil configuration flow device shown in FIG. 3.

FIG. 5 provides a perspective schematic view of the flow plates of theflow device shown in FIG. 3.

FIG. 6 provides a (A) side view; and (B) detailed view of the generationsection of the flow device illustrated in FIG. 3.

FIG. 7 provides a perspective view of one form of the hydrofoil used inthe flow device illustrated in FIG. 3.

FIG. 8 provides a perspective view of another form of the hydrofoil usedin the flow device shown in FIG. 3, in which (A) is a front view; and(B) is a cross-sectional view along line A-A of FIG. 8A.

FIG. 9 provides a cross-sectional view of a dual body injectionhydrofoil used in the flow device illustrated in FIG. 3.

FIG. 10 illustrates various fluid introduction arrangement apertureconfigurations which can be used in the hydrofoil used in the flowdevice illustrated in FIG. 3.

FIG. 11 provides a (A) plan view; and (B) front sectional view ofanother form of the second embodiment of a fibre generation device ofFIG. 3.

FIG. 12 provides a perspective view of a second embodiment of a fibregeneration device according to the present invention.

FIG. 13 provides the configuration and dimensions of the hydrofoil andchannel used in an experimental apparatus according to the presentinvention.

FIGS. 14 to 19 provide optical microscope images of fibres produced fromthe experimental apparatus of FIG. 13.

DETAILED DESCRIPTION

FIGS. 1 to 12 illustrate different embodiments of a fibre producingapparatus 200, 500 according to the present invention. Each embodimentof the apparatus 200, 500 of the present invention can be used toproduce bodies, such as fibres, using a process described in detail inInternational application No. PCT/AU2012/001273, again, the contents ofwhich are incorporated into this specification by this reference.

As taught in International publication No. WO 2013056312 A1 the processincludes the general steps of:

introducing a stream of body-forming fluid into a dispersion mediumhaving a viscosity in the range of from about 1 to 100 centiPoise (cP);

forming a body such as a filament from the stream of body-forming fluidin the dispersion medium;

and where conditions (developed shear stress) are appropriate

shearing the body under conditions allowing fragmentation of thefilament.

The apparatus of the present invention is configured to optimiseconditions of the steps of introducing the body-forming fluid into alaminar flow of dispersion medium and accelerate the dispersion mediumand body-forming fluid therein in order to draw and form a desired body.This acceleration may also cause the formed body (for example afilament) to break, through the creation of the required tensile stressin the body and/or shear rates in the dispersion medium.

Referring firstly FIG. 1, there is shown a general overview of a firstembodiment of a fibre forming apparatus 200 according to the presentinvention. The illustrated apparatus 200 comprises a flow circuit 202,through which a dispersion medium, such as a solvent, circulates. Theflow circuit 202 includes three fluidly connected units 201, 203 and205. Firstly, a solvent reservoir or tank 201 in which a volume of theselected dispersion medium is collected, prior to feeding through theflow circuit. The inlet to a pump arrangement 203 is fluidly connectedto the solvent tank 201. The pump arrangement 203 pumps the dispersionmedium into a fluidly connected flow device 205. The pump arrangement203 can comprise any suitable pump, including but not limited topositive displacement pump rotary positive displacement pumps,reciprocating positive displacement pumps, gear pumps, screw pumps,progressing cavity pumps, roots-type pumps, peristaltic pumps, plungerpumps, triplex-style plunger pumps, diaphragm pumps, rope pumps,impeller pumps, impulse pumps, hydraulic ram pumps, velocity pumps,centrifugal pumps, radial-flow pumps, axial-flow pumps, mixed-flowpumps, eductor-jet pumps, gravity pumps or a combination thereof. Fibresare formed in the flow device 205 as explained in detail below. Thedispersion medium, with nanofibres therein, flows through to the solventtank 201 where the dispersion medium can be recirculated through theflow circuit 202. The generated fibres can be extracted prior to or fromthe solvent tank 201 using any number of standard solid-liquidseparation techniques, such as filtration, centrifugal extraction,flotation or the like.

The second fibre forming apparatus 200 also includes a body-formingfluid pump 207, which injects the selected body-forming fluid into theflow device 205 as will be described in more detail below. Again, thebody-forming fluid pump 207 can comprise any suitable pump, includingbut not limited to positive displacement pump rotary positivedisplacement pumps, reciprocating positive displacement pumps, gearpumps, screw pumps, progressing cavity pumps, roots-type pumps,peristaltic pumps, plunger pumps, triplex-style plunger pumps, diaphragmpumps, rope pumps, impeller pumps, impulse pumps, hydraulic ram pumps,velocity pumps, centrifugal pumps, radial-flow pumps, axial-flow pumps,mixed-flow pumps, eductor-jet pumps, gravity pumps or a combinationthereof. In some embodiments, the body-forming fluid pump 207 comprisesa syringe pump or a peristaltic pump.

As mentioned above, fibre generation occurs in the flow device 205. Theflow device 205 can have a number of configurations, two of which areillustrated in FIG. 2. Each configuration uses different methods todevelop laminar flow at the flow-merge location.

FIG. 2 illustrates a first embodiment of the flow device 205A in whichtwo separate flow conduits 225 converge at merge location 245, and thenflow into a flow constriction 227. The flow device 205A therefore hasthree distinct sections:

-   -   a first flow section 226A, comprising an inflow section        comprising the two separated flow conduits 225A and 225B each        having a conduit height h_(inflow);    -   a second flow section 228A, comprising an outflow conduit 229A        having a conduit height h_(outflow); and    -   a third flow section 230A located between the first 226A and        second flow section 228A of having a transitory cross-sectional        area which tapers (in the illustrated embodiment at about 10°,        although it should be appreciated that the exact angle can vary)        between the first 226A and second flow section 228A.

As shown in the figures, the combined flow area provided by the combinedconduit height 2×h_(inflow) of the separate conduits 225A and 225B ofthe first section 226A is greater than the conduit height h_(outflow) ofthe outlet conduit 229A of the second flow section 228A. Thecross-sectional area of the first flow section 226A is therefore greaterthan the cross-sectional area of the second flow section 228A. Thisdimension change forms a flow constriction, starting at the constrictionentrance 227 in the third flow section 230A. The flow constrictionpreferably comprises a reduction in cross-sectional area between thefirst flow section 226A and second flow section 228A of at least 50%,more preferably at least 60%, yet more preferably at least 70%, and mostpreferably at least 75%. However, it should be appreciated that theexact dimensions would depend on the size and configuration of the flowdevice 205A and apparatus 200.

The fluid flow in the separate conduits 225A and 225B is controlled toprovide laminar flow through the conduits 225A and 225B and to the mergelocation 245. The combined flow then flows through outlet conduit 229A.As can be readily understood, laminar flow can be produced throughoptimisation and control of various flow parameters, including flowvelocity, conduit configuration, fluid properties and the like.

The flow-merge location 245 includes one or more fluid introductionapertures 249 located at or proximate the merge edge 245A configured tofeed the body-forming fluid into the dispersion medium. As noted above,the flow in the separate conduits 225A and 225B is controlled to providelaminar flow through the conduits 225A and 225B and to the mergelocation 245. The location of the fluid introduction apertures 249 atthe merge edge 245A therefore provides a smooth transition between outerdispersion medium flow and the injected flow of the body-forming fluid.Each of the apertures 249 are fluidly connected to a conduit 251 whichruns through a separating element 241 between the conduits 225A and 225Band fluidly connects to a central feeding channel 253 in the separatingelement 241. The separating element 241 can be any wall(s), plate(s) orbody(ies) used to separate the two flow conduits 225A and 225B in theflow device 205A. The central feeding channel 253 is fluidly connectedto the body-forming fluid pump 207 (FIG. 1) which feds the body-formingfluid to the fluid introduction apertures 249 at a desired flow rate.

It is noted that the merge edge 245A is spaced away upstream of theconstriction 227 and start of the second flow section 228A, with themerge edge 245A positioned within the third flow section 230A. Thiscreates a separate body-forming fluid introduction zone proximate themerge edge 245A and acceleration zone within the second flow section228A.

The illustrated flow conduits 225A, 225B and 229A can have any suitableconfiguration and cross-sectional shape. In some embodiments, the flowconduits 225A, 225B and 229A have a circular, oval, square, rectangularor other regular polygon cross-sectional shape. In some embodiments, theflow conduits 225A, 225B and 229A are formed between two spaced apartplates 208A and 209A having a divider plate 241 located therebetween.

FIGS. 3 to 11 illustrate a second embodiment of the flow device 205B foruse in the apparatus 200 shown in FIG. 1. As shown in FIG. 3, thisembodiment of the flow device 205B separates a single inflow 225 ofdispersion medium into two separate flow paths 225C and 225D using ahydrofoil 240.

As best shown in FIG. 7, the illustrated flow device comprises a fluidtight casing 206 which houses a pair of spaced apart plates, an upperplate 208, and a lower plate 209, between which the dispersion mediumflows. The fluid tight casing 204 comprises an elongate tubular body 210having a rectangular cross-section. The tubular body 210 includes a top212 and a base 214 which lie substantially parallel with each plate 208.The tubular body 210 includes two flanged ends 215. End plates 216 and217 are fluidly sealed onto the ends of flanged ends 215 using a seriesof fasteners 218, in this case bolts and fastening nuts. A fluid seal,such as an O-ring (not illustrated) is sandwiched between the respectiveend plates 216 and 217 and flanged ends 215. An inlet header 220 andoutlet header 222, comprising conical or flared conduits are formed inthe end plates 216 and 217, and are used to fluidly connect a flow pathbetween the plates 208 and 209 with the flow circuit 202.

The upper plate 208 is movably attached to the top 212 of the elongatetubular body 210 through a series of adjustable fasteners 216 (two ofwhich are shown in FIG. 7), illustrated as bolts. Similarly, the lowerplate 209 is movably attached to the base 214 of the elongate tubularbody 210 through a series of adjustable fasteners 217 (two of which areshown in FIG. 7), illustrated as bolts. The distance between the top 212and the upper plate 208 and the distance between the base 214 and thelower plate 209 can be adjusted by rotating the respective adjustablefasteners 216 and 217, and thereby adjusting the position of the upperplate 208 or lower plate 209 on that fastener. It should be appreciatedthat other attachment and adjustable arrangements could equally be used,and that these fall into the spirit and scope of the present invention.

The plates 208 and 209 held within the flow device 201 are bestillustrated in FIGS. 3 to 7. As shown in those figures, the platescomprise two spaced apart plates forming a gap G between the platesthrough which the dispersion medium flows. The gap G has three distinctsections:

-   -   a first flow section 226, comprising an inflow section having a        gap height H_(inflow) (FIG. 3);    -   a second flow section 228, comprising an outflow section having        a gap height H_(outflow) (FIG. 3); and    -   a third flow section 230 located between the first 226 and        second flow section 228 of having a transitory cross-sectional        area which tapers at about 10° between the first 226 and second        flow section 228.

As shown in the figures, H_(inflow) is greater than H_(outflow), makingthe cross-sectional area of the first flow section 226 greater than thecross-sectional area of the second flow section 228. This dimensionchange forms a flow constriction 227 in the third flow section 230. Theflow constriction preferably comprises a reduction in cross-sectionalarea between the first flow section and second flow section of at least50%, more preferably at least 60%, yet more preferably at least 70%, andmost preferably at least 75%. In the illustrated embodiment, the gapbetween plates preferably reduces from H_(inflow) of 9 mm to H_(outflow)of 2 mm. However, it should be appreciated that the exact dimensionswould depend on the size and scale of the apparatus 200.

The dimension of the gap between the first flow section (H_(inflow)) andthe second flow section (H_(outflow)) between the plates 208 and 209 canbe varied by altering the positioning of the two plates 208, 209 withinthe casing 204 using the adjustable fasteners 218 as described above.

Hydrofoil 240 (best illustrated in FIGS. 4 and 7) is located between theplates 208, 209 and substantially within the third flow section 230 ofthe gap G. It is noted that the trailing edge 244 of the hydrofoil 240is spaced away upstream of the start of the second flow section 228,with the trailing edge 244 positioned within the third flow section 230.This creates a separate body-forming fluid introduction zone proximatethe trailing edge 244 of the hydrofoil 240 and acceleration zone withinthe second flow section 228 of the gap G.

As best shown in FIG. 4, the hydrofoil 240 assists in the accelerationof the dispersion medium proximate and following the trailing edge 244of the hydrofoil 240 in order to draw and form a fibrous polymerfilament from the body-forming fluid introduced from the trailing edge244 of the hydrofoil 240. The fluid acceleration zone follows thetrailing edge 244 of the hydrofoil 240, and is enhanced by the flowconstriction 227 in the second flow section 228 and third flow section230. Again, this fluid acceleration may also create the required tensilestress in the body and/or shear rates in the dispersion medium tofragment the body formed by the body-forming fluid in the dispersionmedium.

While not wishing to be bound by any one theory, it is thought that theacceleration zone following the trailing edge 244 of the hydrofoil 240(created by the hydrofoil and the flow constriction in the second flowsection 228 and third flow section 230) accelerates the dispersionmedium and formed body through the second flow section 228, inducing thedevelopment of an extensional flow field. The body, in the case of theillustrated example in FIG. 4, a fibre, transported by the fluid isstretched in response to the acceleration of the dispersion medium. Thevelocity difference between the second flow section 228 and third flowsection 230 result in a tensile stress within the fibre. Shear stresscan also be applied by the flow characteristics of the surroundingdispersion medium. The body, in this case, a fibre, fragments if themaximum stress in and applied to the body exceeds the tensile strengthof the fibre.

The illustrated hydrofoil 240 has a linear configuration and issubstantially symmetrical about a chord line X-X (FIG. 3) between theleading face 242 and trailing edge 242 of the hydrofoil 244. As isunderstood in the art, the chord line X-X of a hydrofoil 240 is astraight line connecting the leading edge 248 and trailing edge 244 ofthe hydrofoil 240. The leading face 242 of the illustrated hydrofoil 240comprises a rounded or curved surface. Furthermore, the trailing edge244 of the hydrofoil 240 comprises a substantially flat edge. Thehydrofoil 240 also a tapered body 245 which tapers by about 10° (angle øin FIG. 5, angle α is 160°) between the leading face 242 and trailingedges 244 thereof relative to the cord line X-X, therebetween.Advantageously, this configuration also creates laminar flow at orproximate the trailing edge 244 of the hydrofoil 240.

In some embodiments (not illustrated), the tapered body 245 of thehydrofoil 240 includes at least one curve or wave along the longitudinallength of the tapered body 245. In some embodiments, the tapered body245 of the hydrofoil 240 includes a plurality of curves or waves alongthe longitudinal length thereof in order to create a desired flowpattern across the hydrofoil 240.

The hydrofoil 240 is positioned between the plates 208 and 209 with thetrailing edge 244 of the hydrofoil 240 proximate the transition from thethird flow section 230 to the second flow section 228. The leading face242 of the hydrofoil 240 is located within an end portion of the firstflow section 226, immediately prior to the third flow section 230. Asbest shown in FIG. 11, the hydrofoil 240 also attached to the casing210, with the side edges 243 of the hydrofoil being attached to theadjacent side of the casing 210. This connection can be any suitablefastening or connection arrangement including fasteners, rivets,mounting brackets, snap fasteners or the like. The connection preferablyallows the hydrofoil 240 to move within the gap G, more preferably pivotabout the connection point between the plates 208, 209. This enables thehydrofoil 240 to self-align in the flow of the dispersion medium,thereby ensuring symmetric flow around the hydrofoil 240 and at thefluid introduction apertures 250 (described below).

In use, the pump arrangement 203 pumps the dispersion medium into theinlet header 220 of the flow device 205B, between the plates 208 and 209and across the hydrofoil 240. The dispersion medium can therefore bepumped over the hydrofoil 240 at a desired flow rate to accelerate thebody-forming fluid in order to draw and form a fibrous polymer filamentat the trailing edge 244 of the hydrofoil 240.

In this embodiment, the acceleration and constriction of the dispersionmedium and body forming fluid therein following the trailing edge 244 ofthe hydrofoil 240 and within the third flow section 230 createsconditions allowing fragmentation of the formed body. Where the body isa filament, this results in the formation of fibres, typically shortfibres. The shearing or fragmentation of the formed body, for example afilament to provide the fibres, may be carried out at a suitable shearstress. In the illustrated embodiment, the configuration of thehydrofoil 240, third flow section 230 and flow velocity of thedispersion medium across the hydrofoil 240 from the leading face 242 tothe trailing edge 244 thereof creates a shear in the dispersion mediumat the trailing edge of the hydrofoil where the linear fluid speed is atleast 0.2 m/s, preferably between 0.2 to 20 m/s, more preferably between0.3 to 10 m/s. In some embodiments, fragmentation can result through thedevelopment of shear stresses in the range of from about 100 to about190,000 cP/sec.

While one hydrofoil 240 is illustrated, it should be appreciated thatmulti-hydrofoil systems are also possible and within the scope of thepresent invention. The multi-hydrofoil systems may have the hydrofoilsaligned side by side, stacked, placed in parallel, in series or thelike.

As best illustrated in FIG. 7, the hydrofoil 240 includes a plurality offluid introduction apertures 250 located at or proximate the trailingedge 244 configured to feed the body-forming fluid into the dispersionmedium. As discussed above, the hydrofoil 240 is configured to providelaminar flow at its trailing edge 244. The location of the fluidintroduction apertures 250 at the trailing edge 244 therefore provides asmooth transition between outer dispersion medium flow and the injectedflow of the body-forming fluid. Each fluid introduction aperture 250 isspaced apart by dimension F along the longitudinal length of thehydrofoil 240. Each of the apertures 250 are fluidly connected to aconduit 252 which runs through each hydrofoil 240 and fluidly connectsto a central feeding channel 254 in the hydrofoil 240. The centralfeeding channel 254 runs substantially longitudinally through the lengthof the hydrofoil 240. That central feeding channel 254 is fluidlyconnected to the body-forming fluid pump 207 (FIG. 1) which feds thebody-forming fluid to the fluid introduction apertures 250 at a desiredflow rate.

The use of multiple fluid introduction apertures 250 provides a means tohave large fibre production rate.

Again, the body-forming fluid may be injected into the dispersion mediumat a rate in a range selected from about 0.0001 L/hr to about 10 L/hr,or from about 0.1 L/hr to 10 L/hr. When the body-forming fluid is abody-forming solution, such as a polymer solution, the body-formingsolution may be injected into the dispersion medium at a rate in a rangeselected from the group consisting of from about 0.0001 L/hr to 10 L/hr,from about 0.001 L/hr to 10 L/hr, or from about 0.1 L/hr to 10 L/hr.

One skilled in the relevant art would understand that the rate at whicha body-forming fluid is introduced to the dispersion medium may bevaried according to the scale of the flow device 205 and apparatus 200,the volume of body-forming fluid employed, and the desired time forintroducing a selected volume of body-forming fluid to the dispersionmedium. In some embodiments it may be desirable to introduce thebody-forming fluid into the dispersion medium at a faster rate this mayassist in the formation of fibres with smoother surface morphologies.

The use of a hydrofoil 240 enables the fluid introduction apertures 250to have a number of different shapes and configurations, whilst stillmaintaining control on the flow of the dispersion medium flowing tothose fluid introduction apertures 250. Therefore, while notillustrated, it should be appreciated that the fluid introductionapertures 250 could have any number of shapes including star shaped,oval shaped, any number of regular polygons such as triangular, square,rectangular, pentagonal, octagonal or the like.

As illustrated in FIG. 8, the hydrofoil 340 can have a cylindrical orelliptical geometry, with the leading face 342 and trailing edge 344having an annular configuration, being centred about a hydrofoil centerpoint Y. As shown in FIG. 8(B), this hydrofoil 340 has a toroidal shape,having a taper between the leading face 342 and trailing edge 344. Thehydrofoil 340 includes a plurality of fluid introduction apertures 250circumferentially located and spaced apart around the trailing edge 344.Similar to the hydrofoil 150 shown in FIGS. 6 and 8, each of the fluidintroduction apertures 350 are fluidly connected to a conduit 352 whichruns through each hydrofoil 340 and fluidly connects to a centralfeeding channel 354 in the hydrofoil 340. The central feeding channel354 runs annually around the circumference of the hydrofoil 240. Thatcentral feeding channel 354 is fluidly connected to a body-forming fluidfeed pump (not illustrated) which feds the body-forming fluid to thefluid introduction apertures 250 at a desired flow rate. The hydrofoil340 would preferably be suspended in a conduit using one or moresupports or braces. While not illustrated, it should be appreciated thatthe fluid connection to a body-forming fluid feed pump (for example pump207 shown in FIG. 1) would likely be positioned in one or more of thosebraces/supports. In use, the dispersion medium would flow through theinner void and outer surfaces of the hydrofoil 340.

While not illustrated, it should be appreciated that the fluidintroduction apertures 250 could be fluidly connected to at least twodifferent body-forming fluids. This enables a fibre to be formedincluding two different materials.

As illustrated in FIG. 9, the fluid introduction apertures 450 in someembodiments of the hydrofoil 440 can be fluidly connected to twoconduits or channels 452A and 452B through which the body-forming fluidflows. In the illustrated embodiment, each conduit or channel 452A and452B is connected to a separate central feeding channel 454A and 454Bwhich feed a selected body-forming fluid to the respective conduits 452Aand 452B. The separate conduits 452A and 452B join at a merge section455 located proximate to the fluid introduction apertures 450. The mergesection 455 comprises a Y junction in the illustrated embodiment, butmay comprise a T junction or other junction configuration in otherembodiments. The merge section 455 also includes a short conduit fluidlyconnected to the fluid introduction aperture 250. This arrangementprovides a means to “pre-mix” different body-forming fluids thanks tolaminar-flow channels to obtain multi-domain fibres.

As shown in FIG. 10, the fluid introduction apertures 250 can comprisevarious shapes and configurations. For example, the fluid introductionapertures 250 could comprise a circular (FIG. 10( a) to (e)), star (FIG.10( f)), square ((FIGS. 10( g) and (h)), cross (FIG. 10( i)) orrectangular/slot shape (FIG. 10( j)). It should be appreciated that theaperture 250 could comprise a large number of other shapes over andabove those illustrated in FIG. 10.

As illustrated in FIGS. 10 (c), (d) and (h), the fluid introductionaperture 250 could comprise two or more proximate and aligned apertures250, each aperture 250 being fluidly connected to a differentbody-forming fluid. This enables the respective body-forming fluids tooverlap, intertwine or at least interact in some way when introducedinto the dispersion medium. Additionally, this allows fibreconfigurations to be formed with two different materials having anintertwined, mixed or otherwise interconnected fibre configuration. Theaperture 250 shown in FIG. 10( c) comprises two side by side fluidintroduction apertures 250X and 250Y formed in a circular aperture. Eachof the fluid introduction apertures 250X and 250Y would be fluidlyconnected to a separate body-forming fluid feeding arrangement (conduit252 and central feeding channel 254). Similarly, the aperture 250 shownin FIGS. 10( d) and (e) comprises four side by side fluid introductionapertures 250E, 250F, 250J and 250K formed in a circular or squareaperture. Again, each of the fluid introduction apertures 250E, 250F,250J and 250K would be fluidly connected to a separate body-formingfluid feeding arrangement (conduit 252 and central feeding channel 254).

As shown in FIGS. 10( b) and (e), the fluid introduction apertures 250comprise two or more concentrically arranged or overlapping apertures.This can produce a fibre within fibre configuration, where a first fibreis encapsulated or otherwise formed within another fibre. A firstmaterial can be encapsulated within a second material in thoseembodiments in which the at least two of the at least two apertures arefluidly connected to different body-forming fluids. The aperture 250shown in FIG. 10( b) comprises two concentrically arranged circularfluid introduction apertures 250M and 250N. Similarly, the aperture 250shown in FIG. 10( e) comprises two overlapping arranged circular fluidintroduction apertures 250M and 250N. The inner fluid introductionaperture 250N is formed within outer fluid introduction aperture 250M,and is positioned off-centre with respect to outer fluid introductionaperture 250M. Each of the fluid introduction apertures 250M and 250Nwould be fluidly connected to a separate body-forming fluid feedingarrangement (conduit 252 and central feeding channel 254).

The fluid flow in the first flow section 226 of the conduit can have anysuitable flow characteristic, including laminar, turbulent or the like.In preferred embodiments, the fluid flow arrangement forms a laminarflow in the first flow section 226. In order to assist in laminar flow,a number of diffuser baffles 276 are located at the start of the firstflow section 226 which, in use, contacts the dispersion medium flowupstream of the hydrofoil 240.

Referring now to FIG. 12, there is shown a second apparatus 500 forproducing bodies such as fibres and/or short nanofibres. The illustratedapparatus 500 includes a fluid container 502 forming a fluid housingconfigured to house a dispersion medium 504; a stirrer or mixerarrangement 506, which includes a drive element 508, in this case amotor, connected to a shaft 510 having an impeller arrangement 512immersed in the dispersion medium 504. The impeller arrangement 512includes two hydrofoils 514 arranged 180° apart about the impeller. Eachhydrofoil 514 has a leading face 516 and trailing edge 518. Thehydrofoils 514 are rotatably driven in the dispersion medium 504 in thedirection of the arrows A by the drive element 508 to cause thedispersion medium 504 to flow across each hydrofoil 514 from the leadingface 516 to the trailing edge 518 thereof.

Each hydrofoil 514 includes a plurality of fluid introduction apertures520 located at or proximate the trailing edge configured to feed thebody-forming fluid into the dispersion medium. Each of the apertures 520are fluidly connected to a conduit which runs through each hydrofoil 514and through the shaft 510 to a connection conduit 522. The connectionconduit 522 is fluidly connected to a pump (not illustrated) such as aperistaltic pump, syringe pump of the like, which feds the body-formingfluid to the fluid introduction apertures 520 at a desired flow rate.

The body-forming fluid may be injected into the dispersion medium at arate in a range selected from about 0.0001 L/hr to about 10 L/hr, orfrom about 0.1 L/hr to 10 L/hr. When the body-forming fluid is abody-forming solution, such as a polymer solution, the body-formingsolution may be injected into the dispersion medium at a rate in a rangeselected from the group consisting of from about 0.0001 L/hr to 10 L/hr,from about 0.001 L/hr to 10 L/hr, or from about 0.1 L/hr to 10 L/hr.

Again, a person skilled in the relevant art would understand that therate at which a body-forming fluid is introduced to the dispersionmedium may be varied according to the scale of the apparatus 500, thevolume of body-forming fluid employed, and the desired time forintroducing a selected volume of body-forming fluid to the dispersionmedium. In some embodiments it may be desirable to introduce thebody-forming fluid into the dispersion medium at a faster rate this mayassist in the formation of fibres with smoother surface morphologies.

The fluid container 502 can comprise any suitable receptacle, container,vessel or other bulk liquid retaining body which can house thedispersion medium 504. The exact container would depend on the scale ofthe apparatus. For bench scale production, a beaker or other bench topcontainer could be used. For larger scale production, it is envisagedthat a large mixer process vessel or the like would be suitable.

The configuration of the hydrofoils 514 creates the necessaryacceleration of the body-forming fluid in order to draw and form adesired body such as a particle or fibrous polymer filament from thebody-forming fluid introduced at the trailing edge 518 of the hydrofoil514. Again, the flow pattern and fluid acceleration may also cause fluidconstriction in the dispersion medium proximate and/or following thetrailing edge 518 of the hydrofoil 514. In some cases, the accelerationcreated can produce the required tensile stress and/or shear rates tofragment that body formed by the body-forming fluid in the dispersionmedium. In the case of formed filaments, that fragmentation can formshort fibres.

The illustrated hydrofoil 514 can have a similar configuration to thehydrofoil 240 described in relation to the flow device 205B of theprevious embodiment.

As previously described, a large number of body-forming fluids anddispersion mediums can be used in the apparatus of the presentinvention. Suitable examples of each of the body-forming fluid(described as a fibre-forming liquid) and the dispersion medium aredescribed in detail in International application PCT/AU2012/001273, thecontents of which are incorporated into this specification by thisreference.

EXAMPLES Example 1 Shear Predictions

In order to determine whether the flow device illustrated in FIGS. 3 to11 can generate the required shear forces under laminar flow, thecalculations shown in this document have been performed. Allcalculations are made with reference to the websitehttp://www.pressure-drop.com/Online-Calculator/index.html and thefollowing list of values:

-   -   Density of Butanol: 805.7 kg m⁻³    -   Viscosity of Butanol: 2.593 10⁻³ kg m⁻¹ s⁻¹    -   Absolute pipe roughness 0.01 mm    -   Pipe width: 10 cm

Volume and Velocity/Shear Calculations

The following pressures per meter of pipe at different velocities andpipe outflow heights (H_(outflow)) have been calculated for arectangular cross-section test pipe having a 10 cm width and the heightspecified in each of the tables.

TABLE 1 1 mm height Velocity (m/s) Pressure (kPa) Volume/s Flow type*0.1 3 0.01 L 0.2 6 0.02 L 0.4 13 0.04 L 0.8 25 0.08 L 1.6 50 0.16 L 3.2100 0.32 L 6.4 374 0.64 T 12.8 1305 1.28 T

TABLE 2 2 mm height Velocity (m/s) Pressure (kPa) Volume/s Flow type*0.1 1 0.02 L 0.2 2 0.04 L 0.4 3.5 0.08 L 0.8 7 0.16 L 1.6 13 0.32 L 3.245 0.64 T 6.4 153 1.28 T 12.8 537 2.56 T

TABLE 3 3 mm height Velocity (m/s) Pressure (kPa) Volume/s Flow type*0.1 0.3 0.03 L 0.2 0.7 0.06 L 0.4 1.4 0.12 L 0.8 2.8 0.24 L 1.6 8 0.48 T3.2 27 0.96 T 6.4 92 1.92 T 12.8 324 3.84 T

TABLE 4 6 mm height Velocity (m/s) Pressure (kPa) Volume/s Flow type*0.1 0.09 0.06 L 0.2 0.18 0.12 L 0.4 0.36 0.24 L 0.8 1.29 0.48 T 1.6 3.40.96 T 3.2 11.4 1.92 T 6.4 38.5 3.84 T 12.8 140 7.68 T *Flow type iseither L = Laminar or T = Turbulent.

The results indicate that laminar flow is possible in each of thespecified conditions for each of the inflow and outflow conduits. It isnoted that the inflow conduit (the first section 226 in FIG. 3) willhave the same volume moving through it as the outflow conduit (thesecond section 228 in FIG. 3) and so will have a lesser pressure, lowerspeed and similar flow type to the outflow (still proportional to theabove values) for the size of conduit selected for the outflow conduit.

Example 2 Apparatus Fibre Generation

The flow device 205B illustrated in FIG. 11 and generally illustrated inFIG. 1 was utilised to generate nanofibres.

The dimensions (in mm) of the flow channel and hydrofoil 240 are shownin FIG. 13. As shown in FIG. 13, the inlet channel section 500 has aheight and depth of 8.92 mm×3 mm depth, and the outlet channel section502 as a height and depth of 1.84 mm×3 mm. The depth of the channelthroughout the device was 3 mm. As shown in FIG. 1, a pump 203 (KDSLegato-270 syringe pump) was used to pump a butanol dispersion mediumheld at ˜15° C. into the inlet header 220 of the flow device 205B,between the plates 208 and 209 and across the hydrofoil 240. The butanoldispersion medium was pumped over the hydrofoil 240 at various flowrates as detailed in table 5. A Poly(ethylene acrylic acid) (PEAA)body-forming fluid held at ˜22° C. was pumped into the central feedingchannel 254 in the hydrofoil 240 at various flow rates using a syringepump 207 (New Era NE-4000), again as detailed in table 5 with thebody-forming fluid flowing between the plates 208 and 209. Theconcentration of the Poly(ethylene acrylic acid) (PEAA) used was alsovaried as detailed in table 5.

TABLE 5 Experimental Conditions and results Dispersion Body MediumForming Fluid PEAA Flow rate Flow rate concentration Fibre (Butanol @(PEAA dispersion wt/(vol-of- Diameter Fibre ~15° C.) @ ~22° C.) solvent)(nm) Image  60 mL/min  7.8 mL/hr 16% 800-1300 FIG. 13 100 mL/min  1.6mL/hr 16% 500-1500 FIG. 14  60 mL/min  7.8 mL/hr 12% 400-2100 FIG. 15200 mL/min 23.5 mL/hr 12% 900-3000 FIG. 16 200 mL/min 15.7 mL/hr 12%700-2100 FIG. 17 240 mL/min 15.7 mL/hr 12% 750-1600 FIG. 18

Fibres formed in each run were captured from the flow using a 20 mL vialplaced at the outlet of the device. The resulting fibres were then driedon a microscope slide, studied and photographed using an opticalmicroscope (Olympus DP71). The average diameter of the produced fibreswere then determined from these images, the results of which areprovided in Table 5. The optical Images of the fibres produced from eachrun are shown in shown in FIGS. 13 to 18, and correspond to the variousruns as detailed in Table 5.

The results clearly illustrate that the flow device shown in FIG. 11produces short fibres with diameters in the submicron range over a rangeof dispersion medium and body forming fluid flow conditions.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is understood that the invention includes allsuch variations and modifications which fall within the spirit and scopeof the present invention.

Where the terms “comprise”, “comprises”, “comprised” or “comprising” areused in this specification (including the claims) they are to beinterpreted as specifying the presence of the stated features, integers,steps or components, but not precluding the presence of one or moreother feature, integer, step, component or group thereof.

1. An apparatus for producing a body through the introduction of abody-forming fluid into a dispersion medium, the apparatus including: afluid housing configured to house a dispersion medium; at least twoseparated flow paths along which the dispersion medium flows in alaminar flow, each separated flow path comprising a separate flow path,at least two of the separated flow paths converging at a flow-mergelocation; a fluid flow arrangement which, in use, causes the dispersionmedium to flow along each flow path to the flow-merge location; at leastone fluid introduction arrangement located at or proximate theflow-merge location configured, in use, to feed the body-forming fluidinto the dispersion medium; and a flow constriction arrangementproximate to or following the flow-merge location, which in use,constricts and accelerates the dispersion medium flow proximate toand/or following the flow-merge location.
 2. An apparatus according toclaim 1, wherein the flow constriction arrangement includes a reductionin the overall fluid flow cross-sectional area from the flow upstream ofthe flow-merge location compared to the flow downstream of theflow-merge location.
 3. An apparatus according to claim 2, wherein thefluid housing includes at least first flow section having a first fluidflow cross-sectional area and at least second flow section having asecond fluid flow cross-sectional area, the first fluid flowcross-sectional area being greater than the second fluid flowcross-sectional area.
 4. An apparatus according to claim 3, wherein theflow constriction comprises a reduction in fluid flow cross-sectionalarea between the first flow section and second flow section of at least50%, more preferably at least 60%, yet more preferably at least 70%, andmost preferably at least 75%.
 5. An apparatus according to claim 3,wherein the flow-merge location is spaced away upstream of the start ofthe second flow section.
 6. An apparatus according to claim 3, furtherincluding a third flow section located between the first flow sectionand the second flow sections of the fluid housing, the third flowsection having a transitory cross-sectional area, preferably taperingcross-sectional area interconnecting the first and second flow sections.7. An apparatus according to claim 6, wherein the transition in thecross-sectional area of the third flow section comprises between 5 and30°, preferably about 10° taper between the first and second flowsection.
 8. An apparatus according to claim 1, wherein the fluidintroduction arrangement includes at least one aperture.
 9. An apparatusaccording to claim 8, in which the flow-merge location includes aflow-merge edge proximate the location where the at least two separateflows intersect and merge, the at least one aperture being located at orin that flow-merge edge.
 10. An apparatus according to claim 8, whereinthe at least one aperture is fluidly connected to at least two differentbody-forming fluids.
 11. An apparatus according to claim 8, wherein theat least one aperture is fluidly connected to at least two conduits orchannels through which at least one body-forming fluid flows, eachconduit or channel joining at a merge section located proximate to theat least one aperture.
 12. (canceled)
 13. An apparatus according toclaim 11, wherein the merge section comprises a Y or T junction.
 14. Anapparatus according claim 8, wherein the fluid introduction arrangementcomprises at least two proximate apertures, each aperture being fluidlyconnected to at least one body-forming fluid.
 15. An apparatus accordingto claim 14, wherein at least two of the apertures are fluidly connectedto different body-forming fluids.
 16. An apparatus according to claim14, wherein at least two of the apertures are arranged with a firstaperture enclosed within a second aperture.
 17. An apparatus accordingto claim 1, comprising a plurality of fluid introduction arrangementsspaced apart along the flow-merge location.
 18. (canceled)
 19. Anapparatus according to claim 1, wherein the at least two separated flowpaths are separated by at least one hydrofoil located in the fluidhousing, the hydrofoil having a leading face and a trailing edge, thefluid flow arrangement causing the dispersion medium to flow in alaminar flow from the leading face to the trailing edge thereof.
 20. Anapparatus according to claim 19, wherein the fluid introduction elementor elements are located at or proximate the trailing edge of eachrespective hydrofoil. 21.-22. (canceled)
 23. An apparatus according toclaim 19, comprising a plurality of hydrofoils spaced apart within thefluid housing, each hydrofoil including at least one fluid introductionelement located at or proximate the trailing edge of at least one ofeach respective hydrofoil.
 24. An apparatus according to claim 1,further including at least one baffle located in a location in the fluidhousing which, in use, contacts the dispersion medium flow before theflow-merge location. 25.-34. (canceled)